Trench structure having one or more diodes embedded therein adjacent a PN junction

• US 7,132,712 B2
• Filed: 11/05/2002
• Issued: 11/07/2006
• Est. Priority Date: 11/05/2002
• Status: Expired due to Term

• Current Assignee: Semiconductor Components Industries LLC (ON Semiconductor Corporation)
• Original Assignee: Fairchild Semiconductor Corporation (ON Semiconductor Corporation)
• Inventors: Yedinak, Joseph Andrew, Kocon, Christopher Boguslaw
• Primary Examiner(s): WOJCIECHOWICZ, EDWARD JOSEPH
• Application Number:
  US10/288,982
• Publication Number:
  US 20040084721A1
• Time in Patent Office: 1,463 Days
• Field of Search: 257/328, 257/329, 257/331, 257/310
• US Class Current: 257/328
• CPC Class Codes: H01L 29/0653 adjoining the input or output region of a field-effect device, e.g. the source or drain region
• CPC Class Codes: H01L 29/404 Multiple field plate structures
• CPC Class Codes: H01L 29/407 Recessed field plates, e.g. trench field plates, buried field plates
• CPC Class Codes: H01L 29/7802 Vertical DMOS transistors, i.e. VDMOS transistors
• CPC Class Codes: H01L 29/7813 with trench gate electrode, e.g. UMOS transistors trench gate electrodes per se H01L29/4236
• CPC Class Codes: H01L 29/7816 Lateral DMOS transistors, i.e. LDMOS transistors
• CPC Class Codes: H01L 29/7818 the other device being a pn-junction diode
• CPC Class Codes: H01L 29/861 Diodes

Abstract

In accordance with an embodiment of the invention, a semiconductor structure includes a semiconductor region having a P-type region and a N-type region forming a PN junction therebetween. A first trench extends in the semiconductor region adjacent at least one of the P-type and N-type regions. The first trench includes at least one diode therein.

Claims

1. A semiconductor structure comprising:

a semiconductor region comprising a P-type region and a N-type region forming a PN junction therebetween; and

a first trench extending in the semiconductor region adjacent at least one of the P-type and N-type regions, the first trench having at least one diode therein, the at least one diode being at least partially insulated from at least one of the P-type and N-type regions by an insulating layer, wherein no current flows through the first trench when the semiconductor structure is biased in a conducting state, and wherein the at least one diode influences an electric field in at least one of the P-type and N-type regions to thereby increase the blocking voltage of the semiconductor structure.

2. The semiconductor structure of claim 1 wherein the at least one diode is reverse biased during semiconductor structure operation.

3. The semiconductor structure of claim 1 wherein the insulating layer extends along sidewalls of the first trench but is discontinuous along the bottom of the first trench.

4. The semiconductor structure of claim 1 wherein the semiconductor region is an epitaxial layer formed over and in contact with a substrate.

5. The semiconductor structure of claim 1 wherein one of the P-type and N-type regions forms a drift region, the at least one diode being arranged in the first trench so that when the semiconductor structure is biased in a blocking state an electric field induced in the at least one diode influences an electric field in the drift region to thereby increase the blocking voltage of the semiconductor structure.

6. The semiconductor structure of claim 1 wherein one of the P-type and N-type regions forms a drift region, the at least one diode being arranged in the first trench so that when the semiconductor structure is biased in a blocking state an electric field induced in the at least one diode results in a uniform charge distribution in the drift region.

7. The semiconductor structure of claim 1 wherein the at least one diode includes N-type and P-type regions alternately stacked on top of one another in the trench.

8. The semiconductor structure of claim 1 wherein the at least one diode includes N-type and P-type regions alternately arranged adjacent one another parallel to a surface of the semiconductor structure.

9. The semiconductor structure of claim 1 wherein the at least one diode comprises a P-type silicon layer and a N-type silicon layer.

10. The semiconductor structure of claim 1 wherein the at least one diode comprises a P-doped polycrystalline silicon material and a N-doped polycrystalline silicon material.

11. The semiconductor structure of claim 1 wherein the semiconductor structure is a MOSFET further comprising a second trench in the semiconductor region, the second trench having a gate therein and being laterally spaced from the first trench.

12. The semiconductor structure of claim 1 wherein the semiconductor structure is a MOSFET further comprising a planar gate structure along a surface region of the semiconductor region, the gate structure being laterally spaced from the first trench.

13. The semiconductor structure of claim 1 wherein the semiconductor structure is a MOSFET and the first trench further includes a gate over but insulated from the at least one diode.

14. The semiconductor structure of claim 1 wherein the semiconductor structure is a MOSFET further comprising a gate, a drain, and a source, the at least one diode being electrically connected between the drain and source.

15. The semiconductor structure of claim 1 wherein the semiconductor structure is a MOSFET further comprising a drain terminal and a source terminal located along two opposite surfaces of the semiconductor structure, the first trench extending vertically between the drain terminal and the source terminal.

16. The semiconductor structure of claim 15 wherein the at least one diode includes P-type and N-type regions alternately stacked on top of each other.

17. The semiconductor structure of claim 1 wherein the semiconductor structure is a MOSFET further comprising a drain terminal and a source terminal both located along one surface of the semiconductor structure, the trench extending laterally between the drain terminal and the source terminal.

18. The semiconductor structure of claim 17 wherein the at least one diode includes P-type and N -type regions alternately arranged adjacent one another along the lateral dimension.

19. The semiconductor structure of claim 1 wherein the semiconductor structure is a rectifier having an anode terminal electrically connected to one of the P-type and N-type regions and a cathode terminal electrically connected to the other one of the P-type and N-type regions.

20. The semiconductor structure of claim 19 wherein the anode and cathode terminals are located along two opposite surfaces of the rectifier, the first trench extending vertically between the anode and cathode terminals, and the at least one diode comprises P-type and N-type regions alternately stacked on top of each other in the first trench.

21. The semiconductor structure of claim 1 wherein the first trench is a narrow and deep trench extending vertically between two opposite surfaces of the semiconductor structure.

22. The semiconductor structure of claim 1 wherein the first trench is a wide and shallow trench extending laterally parallel to a surface of the semiconductor structure.

39. The semiconductor structure of claim 1 wherein the at least one diode is arranged parallel to a current flow established when the semiconductor structure is biased in an on state.

23. A semiconductor structure comprising:

a semiconductor region having a body region and a drift region forming a PN junction;

a first trench extending at least in the drift region; and

at least one diode in the first trench, the at least one diode being at least partially insulated from at least one of the body and drift regions by an insulating layer, wherein no current flows through the first trench when the semiconductor structure is biased in a conducting state, and wherein the at least one diode influences an electric field in at least the drift region to thereby increase the blocking voltage of the semiconductor structure.

24. The semiconductor structure of claim 23 wherein the at least one diode is reverse biased during semiconductor structure operation.

25. The semiconductor structure of claim 23 wherein the insulating layer extends along sidewalls of the first trench but is discontinuous along the bottom of the first trench.

26. The semiconductor structure of claim 23 wherein the semiconductor region is an epitaxial layer formed over and in contact with a substrate.

27. The semiconductor structure of claim 23 wherein the semiconductor structure is any one of a vertically-conducting MOSFET, a laterally-conducting MOSFET, and a rectifier.

28. The semiconductor structure of claim 23 wherein when the semiconductor structure is biased in a blocking state an electric field induced in the at least one diode influences an electric field in the drift region to thereby increase the blocking voltage of the semiconductor structure.

29. The semiconductor structure of claim 23 wherein when the semiconductor structure is biased in a blocking state an electric field induced in the at least one diode results in a more uniform charge distribution in the drift region.

30. The semiconductor structure of claim 23 wherein the first trench is a narrow and deep trench extending vertically between two opposite surfaces of the semiconductor structure.

31. The semiconductor structure of claim 23 wherein the first trench is a wide and shallow trench extending laterally parallel to a surface of the semiconductor structure.

40. The semiconductor structure of claim 23 wherein the at least one diode is arranged parallel to a current flow through the drift region established when the semiconductor structure is biased in an on state.

32. A semiconductor structure comprising:

a substrate;

an epitaxial layer over and in contact with the substrate, the epitaxial layer having a body region and a drift region forming a PN junction, the drift region being of the same conductivity type as the substrate;

a plurality of laterally spaced trenches each extending through at least a portion of the drift region; and

a plurality of diodes in each of the plurality of trenches, the plurality of diodes in each trench being insulated from the drift region along the trench sidewalls, wherein at least one of the plurality of diodes in each trench influences an electric field in at least the drift region to thereby increase the blocking voltage of the semiconductor structure.

33. The semiconductor structure of claim 32 wherein the plurality of diodes are positioned in each of the plurality of trenches such that an electric field induced in one or more of the plurality of diodes influences an electric field in the drift region such that a blocking voltage of the semiconductor structure is increased.

34. The semiconductor structure of claim 32 wherein each of the plurality of trenches further includes an insulating layer extending along the trench sidewalls but being discontinuous along the bottom of the trench.

35. The semiconductor structure of claim 32 further comprising at least two terminals located along opposite surfaces of the semiconductor structure, the at least two terminals being configured to bias the semiconductor structure during operation,

wherein the plurality of trenches extend vertically between the two terminals, and the plurality of diodes in each trench includes P-type and N-type regions alternately stacked on top of each other in each trench.

36. The semiconductor structure of claim 32 further comprising at least two terminals located along one surface of the semiconductor structure, the at least two terminals being configured to bias the semiconductor structure during operation,

wherein the plurality of trenches extend laterally between the two terminals, and the plurality of diode in each trench includes P-type and N -type regions alternately arranged adjacent one another along the lateral dimension.

37. The semiconductor structure of claim 32 wherein the semiconductor structure is any one of a vertically-conducting MOSFET, a laterally-conducting MOSFET, and a rectifier.

38. The semiconductor structure of claim 32 wherein the plurality of diodes in each trench are reverse-biased during operation.

41. The semiconductor structure of claim 32 wherein the plurality of diodes are arranged parallel to a current flow in the drift region established when the semiconductor structure is biased in an on state.